Surefire gas cost-cutter: Drive slower

Published 4:00 am, Monday, April 28, 2008

Image 1of/1

Caption

Close

Image 1 of 1

Slow car survey. Chronicle graphic by John Blanchard

Slow car survey. Chronicle graphic by John Blanchard

Surefire gas cost-cutter: Drive slower

1 / 1

Back to Gallery

While gas prices at or near $4 a gallon have persuaded some Bay Area motorists to take public transit, join carpools or curse the oil companies, the high cost of fuel has moved few drivers to practice a proven gas-saver - driving slower.

A Chronicle reporter circumnavigated the bay last week - with the cruise control set at 59 mph - and found little company in the slow lane.

In 111 miles of freeway driving during noncommute hours, he passed just 118 slower-moving vehicles. And on some stretches of freeway - most notably Interstate 80 between the MacArthur Maze in Oakland and Vallejo - almost nobody was driving slower than 60 mph.

"When I'm (driving 55) consciously, I look around and see that it's just me," said Jawahar Swaminathan, 31, who drives regularly on Interstate 80 between his home in Richmond and his job in San Francisco. "Even the truck drivers are pulling around me to pass."

"It can make a big difference," said Patricia Monahan, deputy director of clean vehicles for the Union of Concerned Scientists. "If you like to really accelerate fast, if you have a lead foot, that can have a really big impact on fuel economy."

Most cars get the best mileage between 45 and 55 mph, Monahan said. As speeds creep higher, fuel efficiency drops. For every mile per hour over 60 mph, she said, fuel economy drops by an average of around 1 percent.

How much you stand to save depends on a lot of factors. With gas at $4 a gallon, a driver with a long commute - 400 miles a week - and a gas-guzzling vehicle getting only 20 mpg would save $18.74 a week by slowing down dramatically from 75 to 55 mph, extrapolating from the government's most recent figures on the subject. Even a more moderate deceleration - from 70 to 60 mph - would save that driver $11.74 a week.

In contrast, a commuter who started with a smaller carbon footprint - driving 100 miles a week in a car getting 30 mpg - would stand to save only a few dollars a week by slowing down.

The estimates are rough at best. The U.S. Department of Transportation last studied the effect of speed on fuel efficiency in 1997, and its results were based on a fleet of nine vehicles manufactured between 1988 and 1997 - hardly what's on the road today. "Unfortunately this analysis has not been done over, to my knowledge, in the last 10 years," said Monahan's colleague at the Union of Concerned Scientists, senior engineer Jim Kliesch.

Still, the results are striking. Slowing from 70 to 60 mph improved average fuel efficiency by 17.2 percent. A big slowdown - from 75 to 55 mph - improved fuel efficiency by a whopping 30.6 percent.

The need to conserve gasoline is why, in 1974, in the wake of the Arab oil embargo and ensuing fuel shortage, President Richard Nixon ordered the speed limit nationally to be lowered to 55 mph. The limit was lifted to 65 mph in some areas in the late 1980s, and the 55 mph national speed limit was entirely discarded in 1995. And except in backed-up traffic, few motorists have driven that slowly since.

The Chronicle's drive around the bay last week found that even $4 a gallon gas prices haven't persuaded many Bay Area drivers to ease off the gas pedal and save a few bucks.

Driving a Chronicle-issued Chevy Malibu, this reporter hopped on southbound Highway 101 in downtown San Francisco, settled into the slow lane going 59 mph and started counting the cars he passed - which took a while.

Even in the 50 mph zone through downtown, nobody was driving slower than 60. It took a couple miles of driving to tally the first slow-moving fuel saver.

The drive around the bay went south on 101 to San Jose, north on Interstate 880 to the MacArthur Maze in Oakland, north and east on Interstate 80 to Vallejo, across Highway 37 to Novato and south on Highway 101 back to San Francisco. The drive was made in noncommute hours, and traffic was mostly free-flowing. Only freeway driving was counted.

Drivers traveling slower than 60 mph were scarce all around the bay. But they were hardest to find on I-80 from Emeryville to Vallejo, where the Malibu passed just four vehicles.

Slower on 101

Slower drivers were most common across the bay on Highway 101. From Novato to the north end of the Golden Gate Bridge, 49 drivers were traveling slower than 60 mph. Between San Francisco and San Jose on 101, 38 drivers were passed.

On I-880 from San Jose to Emeryville, 27 drivers were moving slower than 60 mph.

Even at 59 mph, it seemed like the Chronicle car was standing still - especially on wide freeways such as I-880 where cars whizzed by in all lanes. Nobody honked, shook their fists or raised any fingers, but several drivers zipped right up to the rear bumper before suddenly swerving to pass. It wasn't clear whether those moves were the result of inattention or attempts at intimidation.

It's a behavior that fuel-conscious drivers have to get used to, say Bay Area residents who have pulled into the slow lane to save gas costs.

"It's scary, and it can be unsafe if you don't know how to drive defensively," said Swaminathan, who's been driving 55 since moving a year ago to the Bay Area from New Jersey, where gas is much cheaper. "A lot of people try to look into the car. I think they expect to see a grandma driving."

Linda Winter-Meiberg, 67, of Tiburon drives to Sacramento once a week to visit her mother. A few weeks ago, she decided to slow down from 72 mph, which is probably an average speed on that stretch of I-80, to 59 mph.

The move has cut her weekly gas bill from $40 to $35 - even as gas prices have risen.

"I try to be courteous by driving in the slowest lane," she said, "but I still get plenty of dirty looks and a lot of people honking at me. I kidded my husband, saying I was going to put up a sign in the rear window saying, 'Drive slower, save gas.' "

But some drivers don't want to ease up on the gas. They say it's unsafe, that their time is more valuable - or that it takes the fun out of driving.

"I won't do it," said George Steffner, 63, a retired engineer who lives in Moraga and tries to conserve by combining short trips. "I didn't do it when it was the law. To tell you the truth, I like going at higher speeds. I feel safer. And I have other ways of saving fuel."

Latest from the SFGATE homepage:

Click below for the top news from around the Bay Area and beyond. Sign up for our newsletters to be the first to learn about breaking news and more. Go to 'Sign In' and 'Manage Profile' at the top of the page.